This invention relates in general to sheet materials and deals more particularly with an improved dielectric laminate having at least one electrostatic dissipative surface and methods for making such a laminate.
The proliferation of electronic products has created a growing need for supporting and packaging materials to protect sensitive electronic components from electrostatic charges during manufacture and use. Many electronic devices, such as printed circuits and microchips, are extremely vulnerable to damage from static discharge. Static charges generated by the normal handling of such electronic devices and resulting from friction, motion, induction and the separation of dissimilar materials, for example, may result in static discharges in the order of ten thousand volts. Sheet materials used in manufacturing, supporting and packaging of such electrostatically sensitive devices must protect against such potentially damaging rapid static discharges.
An ideal packaging material must be lightweight, durable and capable of being readily fabricated into a desired configuration. Glass epoxy laminates have proven particularly satisfactory for this purpose. However, where such material has been used in electronic packaging it has been common practice to provide a post cure application of an antistatic substance or surface coating on a substantial portion of the surface of the material. The additional operation required to apply this antistatic coating adds substantially to the cost of producing the finished product. Further, such an anti-static surface coating is subject to deterioration, normal wear and damage resulting from handling and may require periodic maintenance.
Accordingly, it is the general aim of the present invention to provide a dielectric laminate including at least one integral surface having a resistivity from about 10.sup.5 to 10.sup.12 ohms/sq while retaining other desirable physical properties of the laminate and without the need for a post productive surface coating on the material.